8 upvotes, 0 direct replies (showing 0)
You might want to check out the Modmail Automator[1] Community App.
1: https://developers.reddit.com/apps/auto-modmail
(I suspect there's a reason why Reddit hasn't built in perma-mute capabilities, even with the most abusive users, and reporting those users for harassment seems to continually be ignored.)
So, that Modmail Automator can be configured to re-mute users and archive their replies if they are currently banned. I don't believe it can tell if they were previously muted, but there may be workarounds. The wiki page[2] for that Community App has several sample rules that can get you started.
2: https://www.reddit.com/r/fsvapps/wiki/auto-modmail
I haven't worked on a rule for re-muting a previously-muted user, but I have made a rule that replies with a standard explanation that we don't allow ban evaders, auto-mutes for another 28 days, and archives messages from users who were banned for Ban Evasion (using the Evasion Guard[3] Community App).
3: https://developers.reddit.com/apps/evasion-guard
There's nothing here!